In the fourth entry in Adler-Olsen’s Department Q series, brilliant but hapless head detective Carl Mørck and his assistants—the feisty, demanding Rose and the devious Assad—are faced with a multiple-murder cold case dating back to the 1950s. That’s when Curt Wad, a closet fascist, performed secret involuntary abortions and sterilizations on “the unfit.” Surprisingly, Adler-Olsen manages to mix humor into a novel with such a dark back-story. Chief among the amusements are the extended effects a flu virus has on the department, which the author presents in painfully funny detail, and Mørck’s continuous victimization at the hands of his degenerate cousin. Both are enhanced by narrator Malcolm who treats a description of a bright red, leaky nose with the same crisp approach he might use for a Shakespearean sonnet. Malcolm presents the perennially sighing Mørck with a voice that fluctuates from despairing to wistful to cautiously hopeful, marked by swiftly dissipating moments of elation. There’s a tinge of amusement in Rose’s shrill and angry commands. And the virus-infected Assad speaks with a subdued voice that’s filtered through a stuffy nose. Malcolm is just as effective in rendering the novel’s more serious sections, capturing the smarmy unction and unbridled evil of Wad. A Dutton hardcover. (Dec.)